A conventional yarn-break/yarn-stop detecting device for use in a textile machine comprises light emitter and photoelectric transducer elements incorporated in a grooved housing and positioned in alignment with each other across the groove in the housing. Between the light emitter and photoelectric transducer elements are positioned glass windows which are respectively located adjacent the light emitter and photoelectric transducer elements so that a beam of light emanating from the light emitter element is incident on the photoelectric transducer element through the two glass windows.
In a prior-art yarn-break/yarn-stop detecting device of this nature, it is important that the light emitter and photoelectric transducer elements be arranged in such a manner that the respective glass windows for the light emitter and transducer elements are angled to avoid direct exposure to external light and deposition of dust and flue on the glass windows. If external light is permitted to reach the glass windows, especially the glass window for the photoelectric transducer element, the detecting device may be actuated erroneously in the absence of a failure in the yarn being passed through the detecting device. On the other hand, dust and flue deposited on the glass windows will critically lessen the luminous intensity of the light to be incident on the photoelectric transducer elements through the glass windows.
In order that the light emitter and photoelectric transducer elements in such a manner as to avoid these problems, various restrictions are encountered in designing and engineering the detecting device and adds to the complexity of the overall construction of the device.
When, furthermore, the detecting device is to be installed in the neighborhood of illuminating lamps, it is important that the detecting device be located at a sufficient distance from each of the lamps and arranged so that the glass windows for the light emitter and photoelectric transducer elements are positioned at such angles with respect to the individual lamps that the light emanating from the lamp will not reach the glass windows. This requirement places added restrictions on the installation and placement of the detecting device in a textile machine.
An object of the present invention is to provide an improved yarn-break/yarn-stop detecting device eliminating these drawbacks in prior-art devices of the described nature.